ToonHeads: The Best of the Worst Cartoons Ever was an unaired 2003 Cartoon Network Special [via Metafilter, where you should read John Harris's notes]. Hanna-Barbera, Ruby Spears and Filmation have much to answer for! For all the Scooby-Doo knockoffs and corporate zaniness, though, there's an experimental quality to much of it (at least within the bounds of what was possible on network television) and some surprisingly weird imagery.
An Xennial moment: I never realized that the music from Pac-Land, the 1984 arcade game, was from Hanna-Barbera's Pac-Man, the 1982 TV show. The memory horizon, somewhere in 1983. Which is, oddly enough, about the time the toy money turned up and increased the quality of TV animation. You can thank Ronald Reagan for that, by the way.